Grid-connected current control device of photovoltaic inverter

Abstract

The invention discloses a grid-connected current control device of a photovoltaic inverter, which samples the grid-connected current through a current detection circuit, and divides current waveform into M points according to corresponding phases to perform PI control, wherein a reference value also corresponds to the phase at the moment; the input of the PI control is that the current detection circuit compares a current sampled value of each phase with a current reference value to obtain an error signal of current errors, and then the control quantity em is generated through a PI control link; the control quantity em and a synthesized total control quantity Em are generated into pulse width modulation signals (PWM) of which the duty ratio K changes along with the synthesized total control quantity Em by a pulse width modulation signal generation circuit so as to control the on-off time ratio of a power switching tube in an inverter circuit, thereby achieving the control of the grid-connected current to ensure that the output grid-connected current and grid voltage have same frequencies and phases, and simultaneously the grid-connected current can be controlled to achieve an expected current peak Ipeak.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic inverter grid-connected power generation systems, and more specifically relates to a photovoltaic inverter grid-connected current control device. Background technique [0002] At present, the solar photovoltaic inverter power generation system has been paid attention to by many countries in the world, and the photovoltaic inverter, as a key part of the photovoltaic inverter grid-connected power generation system, has also been greatly developed. Usually, as figure 1 As shown, the photovoltaic inverter grid-connected power generation system is composed of a solar panel array 1 and a photovoltaic inverter 2 . Among them, the photovoltaic inverter 2 includes a maximum power point tracking (MPPT) module 201 , a bus circuit 202 , an inverter bridge circuit 203 and a control circuit 204 , and its function is to convert solar energy into electrical energy and transmit the energy to the grid 3 . ...

AI Technical Summary

Problems solved by technology

However, the commonly used direct PI current control method not only has low accuracy, but also produces current phase shift, which will lead to low working efficiency of the entire inverter, and problems such as phase error and waveform distortion of grid-connected current.

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